نتایج جستجو برای: سن سنجی u pb

تعداد نتایج: 256148  

Journal: :Ekaia 2021

Cala meategia Ossa-Morena Zonaldean (OMZ) kokatzen da, Iberiar Mazizoaren hego-mendebaldean. Hango mineralizazioa nahiko konplexua denez, az- ken urteotan asko eztabaidatu da horren inguruan, baina berriki egin diren ikerketa- lanen arabera, mineralizazioaren zati bat bertan azaleratzen den skarn kaltziko bate- kin erlazionatuta dagoela interpretatu da. Lan honetan skarn-eko granateak datatu di...

2005
Cin-Ty Aeolus Lee

Trace element signatures of mantle xenoliths along an east-west transect extending from the Sierra Nevada to the Colorado Plateau were investigated in this study. Those beneath the Sierra Nevada are highly enriched in fluid-mobile elements (Cs, Pb, U, and Sr) and, in particular, are characterized by low U/Pb and high Sr/Nd. These signatures imply that aqueous fluids derived by dehydration of se...

2013

Uranium is an alpha-emitting, radioactive, heavy metal that occurs naturally in nearly all rocks and soils. Twenty-two isotopic forms of uranium have been identified, mainly associated with nuclear reactor operations or high-energy physics experiments; the most prevalent isotopes found in the environment are the three naturally-occurring isotopes: U, U, and U. Most uranium isotopes undergo deca...

Journal: :Geochemistry, Geophysics, Geosystems 2006

2001
Alfred Hochstaedter Jim Gill Robert Peters Phil Broughton Pete Holden Brian Taylor

[1] Abstract: We propose that across-arc differences in the geochemistry of Izu-Bonin arc magmas are controlled by the addition of fertile-slab fluids to depleted mantle at the volcanic front, and residual-slab fluids to fertile mantle in the back arc without slab melting or contemporaneous back arc spreading. The arc consists of a volcanic front, an extensional zone, and seamount chains (the W...

2007
J. I. Simon M. R. Reid E. D. Young

At Long Valley (LV) model Sr isotope phenocryst ages and absolute U–Pb zircon ages from precaldera Glass Mountain (GM) and caldera-related Bishop Tuff (BT) rhyolites show that these crystals track >1 Myr of evolution of a voluminous rhyolite magmatic system. In detail, strong disparities between the different age populations complicate ideas for a unified model for rhyolite generation, differen...

ژورنال: علوم زمین 2018
ثریا هویس منیژه اسدپور,

توده نفوذی لویکوگرانیتی قالقاچی به وسعت تقریبی 2 کیلومتر مربع، در باختر دریاچه ارومیه و 70 کیلومتری شمال شهر ارومیه قرار گرفته است. این توده به­صورت یک استوک کوچک در درون سنگ­های دگرگونی منسوب به پرکامبرین شامل گنایس، شیست و آمفیبولیت نفوذ کرده است. این محدوده شمالی­ترین بخش زون سنندج- سیرجان است. سن لویکوگرانیت قالقاچی برای اولین بار به­روش LA-ICP-MS دانه­های زیرکن، حدود Ma 8/3 ± 6/558 تعیین ش...

ژورنال: علوم آب و خاک 2005
غلامرضا ثواقبی فیروزآبادی, , حجت امامی, , مهدی شرفاء, ,

Increasing soil contamination by chemicals has become an issue of increasing environmental concern. Leaching of chemicals into and through the vadose zone creats serious problems due to the contamination of the soil matrix, soil solution and groundwater. Therefore, in order to study the effect of the preferential flow, macropores and organic matter on mobility and leaching of the metals such as...

Introduction: Road dust is a group of solid particles that are presented in the urban areas and are originated from both natural and human-induced sources. This study aims to determine concentrations of heavy metals in urban dusts in Behbahan to identify their natural or anthropogenic sources. Materials and Methods: In this study, a total of 20 samples were collected from main roads with diffe...

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